Air drying is to remove moisture from the air. There are two major forms: adsorption type and freezing type.
Refrigerated
The refrigerated compressed air dryer uses the principle of cooling air and lowering the air temperature to condense the moisture in the humid air and precipitate it from the air to obtain drier air.
Adsorption type
The adsorption compressed air dryer uses the principle of pressure swing adsorption. When the humid air passes through the adsorbent, the moisture is adsorbed by the adsorbent to obtain dry air.
The air directly discharged from the air compressor contains many impurities, mainly composed of water, oil and particulate impurities. The working principle of the air dryer is to use the moisture adsorption characteristics of the adsorbent to reduce the moisture content in the compressed air. Generally speaking, the pressure dew point of the outlet air of the air dryer reaches -20℃~-70℃.
Common dryer adsorbents include activated alumina and molecular sieves.
Activated alumina and molecular sieves are both commonly used adsorbents in industrial production and have irreplaceable functions.
Currently, the most commonly used adsorbents for dryers on the market are activated alumina and molecular sieves. In theory, activated alumina can reach a pressure dew point of -50°C. In fact, it can be fully guaranteed to reach -40°C, while molecular sieves can reach a pressure dew point of -70°C. Pressure dew point. In terms of drying performance, it is much stronger than alumina, but the replacement cost is higher.
Molecular sieve is a kind of microporous aluminosilicate crystal. It has the characteristics of uniform pore size, extremely high specific area, good thermal stability, strong adsorption, large internal surface area, and high strength.
It has high thermal stability and chemical stability, and also has the characteristics of screening performance, ion exchange performance, single selection and good adsorption performance. It is usually used in the adsorption cavity of adsorption dryers.